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Abstract:

An apparatus and method for evaluating a hypertonic condition such as
spasticity in a movable extremity are described. The apparatus includes
an accelerometer, a gyroscope, and a sensor-adapted for quantifying force
or pressure. The apparatus further includes a data communication device
adapted for transmitting data signals obtained from the accelerometer,
said gyroscope, and said sensor for processing and real-time display. The
method includes the steps of moving the extremity through a range of
motion about an axis of rotation. During the movement of the limb
parameters such as acceleration, angular velocity, the force applied to
the extremity, and the time duration to move the extremity through the
range of motion are all measured. The measured parameters are then
transmitted to a data processor which processes the data to generate
information that characterizes the hypertonic condition of the extremity
for immediate feedback to the examiner or storage in a database for
monitoring of the patient's condition. In accordance with a further
aspect of the present invention there is described an apparatus and
method for simulating movement of a limb that has a hypertonic condition
based on characterizing information from a real limb.

Claims:

1. Apparatus for evaluating spasticity in a movable extremity of a patient
comprising:an accelerometer for measuring the acceleration of a point on
the extremity during movement thereof in a range of motion of the
extremity;a gyroscope for measuring the angular velocity at which the
extremity moves in the range of motion;a sensor adapted for measuring the
force applied to the extremity as the extremity is moved through the
range of motion;a data communication device adapted for transmitting data
signals from said accelerometer, said gyroscope, and said sensor;a base
on which said data communication device, said accelerometer, said
gyroscope, and said sensor are mounted; andmeans for attaching said base
to the extremity.

2. Apparatus as set forth in claim 1 further comprising a data processor
mounted on said base and connected between said accelerometer, said
gyroscope, said sensor, and said data communication device for processing
the data signals to modify a characteristic of the data signals prior to
their being transmitted by said data communication device.

3. A device as set forth in claim 1 further comprising an electric power
source operatively connected to said accelerometer, said gyroscope, said
sensor, and said data communication device for providing electric power
to said accelerometer, said gyroscope, said sensor, and said data
communication device.

4. An apparatus for simulating movement of a limb that has a hypertonic
condition comprising:an actuator adapted to be driven by a control
signal;an artificial limb attached to said actuator so as to be rotated
by said actuator;a control processor operatively connected to said
actuator for providing the control signal thereto, wherein said control
processor is programmed with parameters of position, velocity, and torque
that represent the motion of a real limb having a hypertonic condition,
whereby the control signal is varied by said control processor.

5. A method of simulating a hypertonic condition in a limb comprising the
steps of:programming a control processor with desired parameters of
position, velocity, and torque that characterize the hypertonic condition
during motion of a real limb;generating a control signal based on said
desired parameters; andapplying the control signal to an actuator that
drives an artificial limb.

Description:

CROSS REFERENCE TO RELATED APPLICATION

[0001]This application is a continuation of U.S. application Ser. No.
11/191,489, filed Jul. 29, 2005, the entirety of which is incorporated
herein by reference.

BACKGROUND OF THE INVENTION

[0002]Hypertonia is a condition of abnormally increased resistance to
externally imposed movement about a joint. It may be caused by or
manifested as spasticity, dystonia, rigidity, or a combination of such
symptoms. Spasticity is a velocity-dependent resistance of a muscle to
stretching. Therefore spasticity can be defined as hypertonia in which
one or both of the following signs are present: (1) resistance to
movement that increases with increasing speed of stretch and varies with
the direction of joint movement, and (2) resistance to movement that
rises rapidly above a threshold speed or joint angle. This form of
hypertonia is common in patients with neurological conditions such as
cerebral palsy, stroke, spinal cord injury, traumatic brain injury, or
upper motor lesions. During clinical evaluation, spasticity manifests
itself as a "catch" or increased resistance during the application of
passive joint range of motion at or above a threshold velocity. The
foregoing definitions are explained in greater detail in Sanger, T. D. et
al., Classification and Definition of Disorders Causing Hypertonia in
Childhood, Pediatrics 111:e89-e97 (2003).

[0003]Clinical classification systems have been designed in attempts to
characterize the spastic reflex. Among the known classification systems
are the Ashworth and the Tardieu systems. The Ashworth classification is
based on the subjective perception of an examiner of the amount of
increased resistance to movement felt during a passive range of motion
maneuver of a patient's limb. The Tardieu system sought to be more
objective and distinguishes specific angles of the limb joint as
references for events during the performance of the passive range of
motion maneuver. Thus, it identifies the spastic reflex by the angle at
which resistance is first detected (R1) and the maximal extent of the
angular range of motion (R2).

[0004]The Ashworth and Tardieu classification systems rely on
examiner-dependent observations. Therefore, they are prone to
subjectivity and variance from examiner to examiner and between
examinations performed at different times.

[0005]Devices designed to objectively quantify muscle function are known.
For example, a computer-assisted hand-held dynamometer (CAHNDY®) was
developed to make dynamic measurements of muscle function. That device
includes a strain gauge force transducer and an electrogoniometer. The
former measures the amount of resistance applied to the limb and the
latter measures the angle of rotation of the limb about an axis,
typically a joint. The signals from the force transducer and the
electrogoniometer are transmitted to a computer where they are processed
to provide graphs of net moment on the limb as a function of the angle of
displacement.

[0006]The MYOTONOMETER® device is a handheld electronic device that is
designed to measure data for quantifying muscle stiffness. It does this
by making a noninvasive assessment of muscle tone when the muscle is at
rest and during contraction of the muscle. The probe measures muscle
displacement under various conditions of applied force.

[0007]The BIODEX system is a manually operated therapeutic and diagnostic
apparatus with an output monitor. It is usually used as an isokinetic
machine to measure knee function and for knee rehabilitation. It has been
used to measure the stretch reflex changes after intrathecal baclofen
dosage adjustments in cerebral palsy patients.

[0008]Although the foregoing devices and systems provide useful
information on muscle function and condition to the clinician, their
utility in reliably and effectively quantifying hypertonia and presenting
data characterizing such conditions is limited. More specifically, the
known devices and systems and devices leave something to be desired with
respect to the processing of the raw data and with respect to the
presentation of the data in user-friendly graphical and absolute value
formats. Accordingly, it would be desirable to have a device or system
that is capable of reliably measuring indicia of hypertonia. It would
also be desired that such a device can be used in a standardized
examination protocol to provide real-time quantitative measurements of
relevant parameters that are objective and reproducible.

SUMMARY OF THE INVENTION

[0009]The disadvantages of the known devices and methods are overcome to a
significant degree by the devices and associated methods according to the
present invention.

[0010]In accordance with a first aspect of the present invention, there is
provided an apparatus for evaluating a hypertonic condition such as
spasticity in an extremity. The apparatus includes an accelerometer, a
gyroscope, and a pressure sensor. A base is provided in the apparatus on
which the accelerometer, gyroscope, and the pressure sensor are mounted.
The apparatus further includes a data communication device adapted for
transmitting data signals from said accelerometer, said gyroscope, and
said pressure sensor. The data transmitted from the apparatus can be
processed locally during therapy or rehabilitation sessions to provide
the examiner or the patient with real-time feedback about the patient's
condition.

[0011]In accordance with a second aspect of the present invention there is
provided a method of evaluating a hypertonic condition such as spastic
reflex of an extremity. The method includes the step of moving the
extremity through a range of motion about an axis of rotation. During the
movement of the limb the acceleration of a point on the extremity, the
angular velocity at which the extremity moves in the range of motion, the
force applied to the extremity as it is moved through the range of
motion, and the time duration to move the extremity through the range of
motion are all measured in real time. The measured acceleration, angular
rate, force, and time, are then transmitted to a data processor which
processes the data to generate information that characterizes the
hypertonic condition of the extremity. As an additional feature of the
method according to this aspect of the invention, the characterizing
information and data are stored in a database for later retrieval and
use.

[0012]In accordance with another aspect of the present invention there is
provided a method for monitoring a hypertonic condition of a patient. The
method according to this aspect of the invention includes the step of
first identifying an extremity of the patient which has a hypertonic
condition. The method continues with the step of moving the extremity
through a range of motion about an axis of rotation. During the movement
of the extremity the acceleration of a point on the extremity, the
angular velocity at which the extremity moves in the range of motion, the
force applied to the extremity as it is moved through the range of
motion, and the time duration to move the extremity through the range of
motion are all measured. The measured acceleration, angular rate, force,
and time, are then transmitted to a data processor which processes the
data to generate information that characterizes the hypertonic condition
of the extremity. The characterizing information is preferably stored in
a database of such information. The information can be retrieved from the
database and compared to previously obtained characterizing information
for the hypertonic condition in the patient so that any change in the
condition as a result of treatment or therapy and changes in the
characteristics of the evaluation or maneuvering of the limb can be
readily determined.

[0013]In accordance with a further aspect of the present invention there
is provided an apparatus for simulating movement of a limb that has a
hypertonic condition. The apparatus according to this aspect includes an
electric motor adapted to be driven by a control voltage. An artificial
limb is attached to the electric motor so as to be rotated by it. A
control processor is operatively connected to the electric motor for
providing the control voltage thereto. The control processor is
programmed with parameters of position, velocity, and torque that
represent the motion of a real limb having a hypertonic condition,
whereby the control voltage is varied by said control processor. The
parameters for programming the simulator are preferably obtained from a
database of such information as described above relative to other aspects
of this invention.

[0014]In accordance with a still further aspect of this invention, there
is provided a method of simulating a hypertonic condition in a limb to
aid in the training of examiners. This method includes the step of
programming a control processor with desired parameters of position,
velocity, and torque that characterize the hypertonic condition during
motion of the limb. The control processor generates a control voltage
based on the desired parameters. The control voltage is applied to an
electric motor that drives an artificial limb, whereby the artificial
limb is rotated in a manner that simulates the movement of a real limb.
The parameters for programming the simulator are preferably obtained from
a database of such information as described above relative to other
aspects of this invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]The foregoing summary as well as the following detailed description
will be better understood when read in connection with the drawings
wherein:

[0016]FIG. 1 is a schematic block diagram of a system in accordance with
the present invention;

[0017]FIG. 2 is a schematic block diagram of a remote device used in the
system shown in FIG. 1;

[0018]FIG. 3 is a schematic block diagram of a data transceiver used in
the system shown in FIG. 1;

[0019]FIG. 4 is a schematic block diagram of a host processor used in the
system shown in FIG. 1;

[0020]FIG. 5 is a partial top plan view of an embodiment of the remote
device shown in FIG. 2;

[0021]FIG. 6 is a schematic view of a human leg showing the use of the
remote device of FIG. 5;

[0022]FIG. 7 is a schematic block diagram of a device for simulating a
subject having a hypertonia condition; and

[0023]FIG. 8 is a schematic diagram of the control processor used in the
simulator device shown in FIG. 7.

DETAILED DESCRIPTION

[0024]Referring now to the drawings, and in particular to FIG. 1, there is
shown a system 10 for quantifying and evaluating hypertonia in a human
subject. The system 10 includes a remote device 12 and a host processor
14 having a data transceiver 16. Various peripheral devices such as a
display monitor 18, a printer 20, and a keyboard and mouse 22 are
operably connected to the host processor 14 to permit data input and
output operations. For example, information such as subject
identification, date and time, and requests for data output displays can
be manually input using the keyboard and mouse 22. The input information
as well as graphs and data charts of measured parameters can be displayed
on the monitor 18 and printed on the printer 20.

[0025]The remote device 12 is preferably embodied as a self-contained
package that can be used remotely from the host processor 14. It is
preferably small and lightweight so that it can be applied to a limb of
the subject to be examined. It is preferably configured for wireless
transmission and reception of data signals, but could be hard-wired to
the host processor if desired. As shown in FIG. 2, the remote device 10
includes sensors 24. Preferably, the sensors include an accelerometer, a
gyroscope, and a force or pressure sensor. The sensors provide data
signals that relate to parameters such as position and displacement of
the subject's limb and the force applied to move it through a range of
motion. The remote device 12 also includes data processing means
connected to the sensors 24 for processing data signals generated by the
sensors. Toward that end a signal preprocessor 26 is connected to receive
data signals from the sensors 24. The signal preprocessor 26 includes
circuits and electronic devices for amplifying the signals, filtering
extraneous information from the data signals, and/or smoothing the
received signals. A further signal processor 28 is connected to receive
the pre-processed data signals from the signal preprocessor 26. The
signal processor 28 includes logic circuits for mathematically deriving
other information from the basic data signals. For example, the signal
processor 28 would be configured to keep track of orientation of the
remote device 12 in space, detect certain types of events based on the
data received, and limit the amount of data that actually needs to be
transmitted to the host processor 14 to provide an accurate
representation of the motion of the limb being examined.

[0026]Once the data signals have been processed, they must be formatted
for transmission to the host processor 14. A data formatting circuit 30
is included in the remote device 12 for that purpose. The data formatting
circuit 30 includes analog-to-digital converters, buffer memory, and data
encoders. A wireless transceiver 32 is connected to receive the encoded
data signals from the data formatting circuit 30. The transceiver 32 is
configured for transmitting the data signals to the host processor 14
using standard wireless protocols. The wireless transceiver also includes
a receiver section to receive command signals transmitted from the host
processor 14. Such signals include commands for turning the remote device
12 on or off, commands to reset the remote device memory registers, and
other utilitarian functions. An onboard power supply 34 is included in
the remote device 12 to provide electric power to the various sensors and
devices. The power supply 34 includes a battery and voltage regulation
circuits as needed to provided a stable source of power to the sensors
24, the signal processing circuits 26 and 28, the data formatting circuit
30, and the wireless transceiver 32.

[0027]Shown in FIG. 5 is a preferred arrangement of the remote device 12.
The remote device 12 has a case 52 for encapsulating the sensors and the
other electronic circuits and devices used in the remote device. A strap
54 is coupled to the case 52 so that the remote device 12 can be attached
to the limb of a patient. An accelerometer 56, a gyroscope 58, and a
pressure transducer 60 are mounted and connected on a circuit board 66.
The accelerometer 56 can be realized by any of the known miniature
accelerometer devices such as those made and sold by Analog Devices under
Model No. ADXL202. The gyroscope 58 can be realized by any of the known
miniature gyroscope devices such as those made and sold by Murata
Manufacturing Co. under the name "GYROSTAR". The pressure transducer can
be realized by any known miniature pressure transducer such as the Model
MPX10 made by Motorola Inc. Also mounted and connected on the circuit
board 66 are the power supply 34 and the electronic circuit devices 64
for processing and transmitting the data signals to the host processor
14.

[0028]Referring now to FIG. 3, there is shown a preferred arrangement for
the data transceiver 16 used in the system according to the present
invention. The data transceiver 16 includes a wireless
transmitter/receiver section 36 which is configured similarly to the
wireless transceiver 32 on the remote device 12. The data transceiver 16
may be embodied as a wireless pc adapter of the types which are widely
available. The wireless transmitter/receiver section 36 receives data
signals transmitted from the remote device 12. The data signals would
include not only data signals from the sensors, but also utility
information such as battery level and error codes produced by any of the
onboard circuits. A data conversion circuit 38 is connected to receive
the data signals from the transmitter/receiver 36. It is configured to
decode the data signals and re-format them for communication to the host
processor 14. A data storage circuit 40 is connected to receive the
re-formatted data signals from the data conversion circuit 38. The data
storage circuit 40 includes data storage devices such as random access
memory modules for buffering the data signals to the host processor 14. A
standard interface connection 42 is connected to receive the data signals
from the data storage circuit 40 for input to the host processor. The
interface connection 42 can be embodied as a PCI adapter, USB connection,
or other standard-type data communication interface. Although the primary
function of the data transceiver 16 is the reception and handling of data
signals from the remote device 12, it is contemplated that it will also
be operable to transmit data signals to the remote device. In this
regard, it would function to transmit commands from the host processor to
the remote device for effecting certain operations in the remote device.
Such operations would include turning the remote device on or off,
clearing memory registers, etc., as described above.

[0029]Referring to FIG. 4, there is shown a preferred arrangement for the
host processor 14 used in the system according to the present invention.
The host processor 14 may be realized as a stand-alone type personal
computer such as a desktop or notebook computer. It is also contemplated
that the host processor 14 could be embodied as a portable hand-held
device such as a PDA, palm pc, or a special purpose device. The host
processor 14 includes a hardware interface 44 for connection with the
data transceiver 16. A data transfer circuit 46 is connected to receive
the data signals from the interface 44. The data transfer circuit 46
includes data storage and handling devices to facilitate transfer of the
incoming data to a permanent storage device, such as a hard disk drive,
and to the central processing unit 48.

[0030]The central processing unit 48 can be any of the known personal
computer-type CPU's such those manufactured and sold by Intel
Corporation, Advanced Micro Devices, or Apple Computer Inc. When the host
processor 14 is embodied as a hand-held device, the central processing
unit would be a CPU for any of the known hand-held devices such as those
manufactured and sold by PALM Inc., Hewlett-Packard Inc., or Dell
Computer Inc. The central processing unit 48 runs the software used to
manipulate the data received from the remote device 12 to provide useful
information to the therapist or physician. The central processing unit 48
runs software that performs additional filtering of the data to remove
unwanted or unneeded signal components. The software would also be
configured to integrate or differentiate the angular velocity and
acceleration data signals from the remote device to calculate an absolute
position in space, to calculate a joint angle or angles as a function of
time, or to quantify aspects of the received data that are relevant to
the motion of the limb or joint kinematics, such as the joint angle and
velocity when as spastic catch occurs. In addition, the software would
permit the graphic representation of desired parameters as a function of
another parameter to graphically illustrate aspects of motion during a
spastic catch or other condition.

[0031]The host processor 14 is programmed to determine several parameters
that can be used to quantify a spastic reflex, including, the angular and
linear velocity of a point on the patient's limb, the angular and linear
acceleration of that point, the absolute position and the change in
position of that point over time, the location and the change in location
of the point over time, and the torque or amount of resistance present
when the limb is moved through its range of motion.

[0032]The quantities measured and calculated by the system 10 according to
the present invention can be used to standardize the description and
characterization of a spastic reflex throughout its range of motion. The
data can also be displayed in real time to provide virtually
instantaneous feedback to the clinician or the therapist. The raw data
generated by the remote device can also be processed to yield a set of
identifying characteristics or parameters that would aid in diagnosing a
disease state.

[0033]It is a further feature of the system according to this invention
that the host processor will run software that provides the ability to
store the received data in a database. The database would be organized
similar to the known medical patient databases and provide for rapid
searching of computerized patient records. The data stored in the
database could be used to track the effect on a hypertonia condition over
time or over a series of therapeutic treatments for the condition.
Additionally, the information in the database would permit a therapist or
medical practitioner to quickly recall and compare response data for
multiple patients who have similar symptoms of hypertonia or have some
other user-specified common criteria. For example, it would be possible
to quickly extract data for all patients that exhibited a specific type
of response as quantified by the sensors in the remote device 12. The
capability to quickly review multiple patients provides a means to assess
outcomes of a group of patients who may be subjected to different
treatments. The information obtained by such an analysis would greatly
assist in deciding which treatment or treatments are most effective for a
particular type of patient. It is further contemplated that the data in
the database can be used to generate parameters for programming a
simulator as described more fully hereinbelow.

[0034]Further, the data and graphical representations of the measured
parameters provided by the system of this invention will standardize the
evaluation of hypertonic spasticity resulting from a neurological
condition. Such standardization is similar to an electrocardiogram (ECG)
that is documented, reproducible, and understood by physicians around the
world. The standardization of the evaluation of the spastic reflex in
patients will have a significant impact on the treatment and management
of neurological conditions. For example, an evaluation of such a
condition performed prior to the patient receiving medical treatment can
be objectively compared to an evaluation done after such treatment. Such
comparisons are difficult, if not impossible, to perform using the
current techniques because the known assessment technique relies
primarily on the skill and experience of the therapist or clinician
performing the procedure.

[0035]Use of the system described above to quantify and represent a
spastic reflex or other hypertonia will now be described in connection
with various methods. Examination for evaluating hypertonia, and more
particularly, a spastic reflex, in an extremity involves moving a segment
of the extremity through a passive range of motion at a preselected
velocity. A proximal segment of the extremity is held stationary in order
to serve as a reference for determining the resistance to movement of the
moving segment and the angle formed between the moving segment and the
proximal segment. By convention, angle at the position of rest or at the
maximum extension of the movable segment is defined as zero (0) degrees.
It will be appreciated that the system described herein can also be used
with active range of motion by the patient himself/herself when desired.

[0036]In geometric terms, the extremity to be tested has at least two
segments at least one of which is movable relative to the other
segment(s). The movable segment has a specified axis of rotation that is
defined to be perpendicular to the plane of motion. A point on the
movable segment is selected at a known distance from the axis of
rotation. That point will move through an arc as the movable segment is
moved through the range of motion. As shown in FIG. 6, a leg 70 has a
thigh segment 74 and a movable segment 76. An axis of rotation is defined
through the knee 78 and would be perpendicular to the plane of the paper.
The movable segment 76 can be rotated about that axis. A point is defined
at the ankle 72 of the leg 70. The remote device 12, described above, is
attached or applied to the movable segment 76 at or adjacent to the ankle
72. The ankle 72 will have a defined acceleration as the movable segment
76 is moved through a range of motion, for example, between points X and
Y, or between points X' and Y'. The acceleration is sensed by the
accelerometer in the remote device 12. The gyroscope in the remote device
12 senses the initial location of the ankle 72 and its change in position
as the movable segment 76 is moved through the range of motion. The
pressure transducer in the remote device 12 senses the force applied to
the leg segment 76 as it is moved through the range of motion. Although
the data accumulation portion of the method according to the present
invention has been described with reference to examination relating to
movement about the knee joint, it is contemplated that data can also be
acquired using the remote device 12 for examinations relating to
movements about the hip, the ankle, the elbow, and any other extremity
that rotates about an axis through a joint.

[0037]It is also a feature of this aspect of the present invention that
more than one remote device can be used during an examination. For
example, in evaluating a hypertonic condition in an arm, a remote device
can be attached or placed on the upper portion of the arm, i.e., above
the elbow, and a second remote device can be applied to the forearm. Such
an arrangement would allow evaluation of more complex movements about
multiple joints. The use of multiple remote devices for collecting data
is facilitated by the use of wireless communication of the data from the
remote units to the central processor. Moreover, the remote device can be
constructed with multi-axis sensors or multiple sensors for measuring the
acceleration, angular velocity, and force in two or three dimensions and
about two or three axes.

[0038]In a preferred format of the examination process, a musculoskeletal
evaluation of the spastic condition using the Ashworth and Tardieu
systems will be performed by the examiner or therapist with the remote
device 12 in place. The examinations will be performed in multiple sets.
Each set of examinations, evaluating the patient's involved and
noninvolved extremities, will consist of passive range of motion
maneuvers performed at various examiner-selected speeds. The actual
speeds are selected to elicit a spastic reflex in the extremity that can
be sensed with the remote device and evaluated.

[0039]The values of the measured parameters, acceleration, angular
velocity, distance, and force, are transmitted to the host processor. The
host processor performs mathematical operations with the parameter values
to obtain additional parameters such as angular displacement and angular
velocity. The various parameters are then displayed, either in real time
or delayed, in graphical forms to provide useful information about the
spastic reflex of the patient being tested. Such graphical
representations may include acceleration as a function of time, angular
displacement as a function of time, and angular velocity as a function of
angular displacement. The graphical data representations are not limited
to the listed examples because others could be readily defined by the
clinician or physician for specific purposes or special hypertonic
conditions. The graphical or other data representations can be stored in
a database for the patient, as described above, for later retrieval as a
basis of comparison, for example, after therapeutic treatment or against
other patients with similar conditions.

[0040]Referring now to FIG. 7, there is shown a simulator device 80 in
accordance with another aspect of the present invention. The simulator
device 80 is adapted to simulate the motion of an extremity of a patient
having a hypertonic condition that results from a neurological disorder.
The simulator device 80 includes an artificial limb 82 that is coupled to
a motor 84. The artificial limb 82 is constructed to be similar to a real
limb, such as an arm or leg, in terms of weight and moment of inertia.
The artificial limb 82 is coupled to the motor 84 in such a manner that
when it is moved by the motor, the motion is similar to that of the limb
being simulated. A control processor 86 is connected to the motor 84. The
control processor 86 is programmed to provide control signals, preferably
a control voltage (Vc) to the motor 84 to drive the motor in a
manner that simulates the movement of a limb. The control processor 86 is
programmed to generate control signals that drive the motor 84 to provide
a limb motion that is normal or one that manifests a hypertonic reflex.
The control processor 86 would include either a logic circuit or a CPU
that executes a software code to generate the desired control signals.

[0041]Shown in FIG. 8 is a preferred arrangement of the control processor
86. The control processor 86 utilizes a feedback loop based on angular
position (θ), angular velocity (ω), and torque (τ)
parameters from the artificial limb 82 and motor 84. Signals representing
those parameters are input to the control processor 86. All of the
parameters are input to an empirical control logic 88. The empirical
control logic 88 is programmed to calculate a desired torque signal
(τD). The actual torque signal and the computed torque signal
are summed at a summing amplifier 90 to provide an error signal
(τD-τ). The error signal is input to the motor control logic
circuit 92 and is used to compute an updated control voltage (Vc).
The empirical control logic 88 is programmed to provide the relationships
between the position, velocity, and torque parameters for different
spastic responses. The computational relationships are based on the
results of testing patients using the system described above. The
computational logic can also be derived from published data and feedback
from physicians who work with patients having a spastic condition.

[0042]A system and method have been described for use in connection with
the quantitative evaluation of a hypertonic condition in a patient. The
system provides a wide scope of utility in connection with the assessment
and treatment of patients having such conditions. The system and method
are useful in the evaluation of hypertonic conditions associated with,
but not limited to the following: cerebral palsy, traumatic brain injury,
cerebrovascular disease such as childhood stroke, chronic spinal cord
injury, hereditary spastic paraparesis, and neurodegenerative disorders
such as metachromatic leukodystrophy, Pelizaeus Merzbacher disease,
neuronal ceroid lipofuscinosis, and Hallervorden-Spatz syndrome. The
system according to this invention can be used to characterize a
hypertonic condition exhibited during a range of motion examination in
terms of velocity, joint angle displacement, muscular resistance,
chronology of events, and duration of events.

[0043]The system and method of this invention can be used to standardize
clinical measurement and evaluation of results and to standardize the
procedure of testing in order to produce reliable, reproducible results
for long term patient follow-up or patient-to-patient comparison.

[0044]The system and method described herein may be used to monitor a
patient's response to medical and/or surgical treatment of spasticity.
Likewise, measurements made using the disclosed system can be used to
characterize the natural history of the disease process.

[0045]The system according to this invention device can facilitate
documentation of a spastic reflex or other hypertonic condition in the
form of easily understandable graphs and tables. Such documentation also
will facilitate communication and exchange of information between health
providers and may be used to help physicians differentiate between
disease conditions. Further, the data in the form of graphs and tables
may be archived in a database for future comparison and for research
purposes.

[0046]The system and method according to the present invention are useful
not only for passive testing, but also for evaluating active, voluntary
motion of patients. In this regard, the system can be used to give
positive real time feedback to patients undergoing therapy and treatment
(e.g., muscle stretching and strengthening). Moreover, the system and
method can be used in connection with other techniques for assessing
muscular activity such as electromyography. In this regard, it is
contemplated that the remote device could incorporate a probe for
electromyography.

[0047]Further, the data acquired with the apparatus and system of this
invention may be used to program and control the operation of a device
for simulating the motion of a limb manifesting a hypertonic condition.
Such simulation can be utilized for educational, research, and training
purposes.

[0048]It will be recognized by those skilled in the art that changes or
modifications may be made to the above-described embodiments without
departing from the broad inventive concepts of the invention. It is
understood, therefore, that the invention is not limited to the
particular embodiments which are described, but is intended to cover all
modifications and changes within the scope and spirit of the invention as
described in the appended claims.